1. Field of the Invention
This invention is generally directed to electrical fuse elements of the flat blade miniature plug-in type which are commonly used in the automotive and electronics industries and more specifically to electrical connectors which may be mounted to such conventional blade fuses for purposes of tapping power from the electrical conductors associated with such fuses. The power taps or tap adaptors of the present invention include a clamp member having spaced leg portions which may be engaged with the top portion of the conventional blade fuse. The clamp member includes a threaded bore which is aligned with a test probe opening in the upper surface of the blade fuse. One of a number of varying configurations of terminal elements may be selectively threaded through the bore in the clamp and brought into electrical contact with a current carrying test tab or portion of the conductor disposed within the fuse. Each terminal element will be provided with a suitable male or female contact so that power, through the fuse, can be selectively supplied to electrical components, instruments or devices for which dedicated or specific fuses have not been provided.
2. History of the Related Art
The use of flat blade miniature plug-in type fuses continues to grow in popularity thereby replacing the more conventional glass cylinder type fuses which have been associated with the automotive and electrical industries. Flat terminal blade miniature plug-in fuses generally include an electrically insulated housing having a pair of conductor blades extending therefrom. The blades are connected within the housing by a thin strip of electrical conducting material which is designed to fail at a given amperage so as to prevent an overload through the fuse when the fuse is placed in an electrical circuit. Such fuses are commonly utilized in the automotive industry to protect circuits including headlight, taillight and courtesy light circuits as well as heater circuits, windshield wiper motor circuits, radio circuits and other related electronic circuits wherein the fuses prevent overloads through such circuits. The housings are generally formed of a translucent or transparent plastic material so that a quick visual indication of a fuse failure may be readily observed through the housing In addition, such conventional fuses normally include one or more openings adjacent the upper portion of the fuse through which a test probe may be inserted so as to contact an electrical tab associated with one of the conducting blades to thereby readily indicate whether or not there is power flowing through the fuse.
A further characteristic of many conventional flat blade terminal fuses is that the upper end of the fuse housing normally incorporates a flanged portion which facilitates the manual handling of the fuse. Some examples of conventional flat terminal blade miniature plug-in fuses are disclosed in Williamson, et al. U.S. Pat. No. 3,909,767, Ciesemier, et al. No. 4,344,060, Greenberg No. 4,499,447, and West German Pat. No. DE 2940607 dated Apr. 16, 1981.
Although the introduction of flat blade miniature plug-in fuses has resulted in a significant improvement in the economy and the handling of fuse elements, especially of the type which are utilized in automotive vehicles and other electrical systems, there remain problems associated with the installation of new electrical equipment for which dedicated fuses have not been provided. In many instances, it may be desired to install auxiliary electrical equipment such as radios, cassette players, televisions, modems and telephones into vehicles such as cars, trucks and vans. When such equipment is installed in a vehicle it must be connected to an electrical circuit of the vehicle's electrical system. Further, to ensure safety of the electrical circuit, such circuits must be connected through fuses so that the circuits are protected from overloads. In the automotive industry, such fuses are normally set at an amperage rating which may vary between five and thirty amps.
Previously, in order to connect auxiliary electrical equipment to an existing electrical circuit, it was necessary to tap one of the electrical wires leading to or from the fuse box or panel associated with the electrical system. Such connections are not only unsafe but require a great deal of experience and knowledge in identifying which electrical lines may be appropriately spliced to provide power to the auxiliary equipment. In addition to being unsafe, such a process is very time consuming and therefore costly. Also, in many instances, the complexity of the electrical wiring or electrical harnesses associated with the circuitry of given equipment and especially automotive equipment is such that an installer must have access to the electrical plans or diagrams associated with the electrical system in order to identify which electrical lines may be utilized for purposes of providing power to auxiliary equipment.
In order to forego many of the difficulties associated with tapping into an electrical line, many installers of auxiliary electrical equipment simply tap into a fuse within the fuse box of an electrical circuit. Generally, an electrical wire from the auxiliary equipment is wrapped around, and in electrical contact with, one of the blade elements associated with a fuse, such as a miniature plug-in fuse, and thereafter the fuse inserted into the appropriate socket. Such a loose connection is not only unsafe but is easily disrupted by vibration or accidental contact. Due to the small dimensions between the terminals of conventional blade fuses, attempts to wrap or otherwise attach supplemental electrical wires to one of the terminals can result in an arcing between the terminals creating a safety problem if the load of the fuse selected becomes excessive or shorted causing the fuse to blow. In instances where the auxiliary electrical line includes a larger gauge of electrical wire, it is difficult to wrap or solder such an auxiliary line to the blades or terminals associated with conventional fuses.
To overcome the obvious unsafe and impractical conventional tapping of electrical fuse elements, in applicants prior U.S. Pat. No. 4,884,050 a blade terminal tap fuse is disclosed which allows for a flat terminal blade miniature type plug-in fuse to be modified to provide an easily accessible source of electrical current. In applicant's patent, one or both of the terminals associated with conventional flat blade fuses are modified so that the electrical contact elements are in spaced relationship with respect to the upper surface of the fuse housing. Therefore, when one of the blades extends above the fuse housing, a simple female connector may be quickly engaged therewith in order to obtain a source of current supply through the fuse. In those instances where the blade element is recessed within the housing, an opening is provided of a size to permit the female connector to be inserted into the upper portion of the housing in order to engage the terminal member and thereby establish a source of electrical power to auxiliary electrical equipment. Unfortunately, such a fuse requires a modification to existing conventional plug-in type fuses of the flat blade type.
There have been other efforts directed to creating electrical taps for use with various types of fuse blocks or fuse boxes and some examples of such prior art tapping devices are disclosed in Cairns et al. U.S. Pat. No. 4,221,455, Sohler No. 4,327,638 and Lobe No. 4,555,638.